Use title-style capitalization for book titles, part titles, chapter titles, section titles
(text heads), disc titles, running footers that use chapter titles, and cross-references to
such titles.

References to specific book elements:

In cross-references to a specific appendix or chapter, capitalize the word Appendix or
Chapter (exception to The Chicago Manual of Style). When you refer to appendixes or
chapters in general, don’t capitalize the word appendix or chapter:

See Chapter 2, “QuickTime on the Internet.”
See Appendix B for a list of specifications.
See the appendix for specifications.

References to untitled sections:

In cross-references to sections that never take a title (glossary, index, table of
contents, and so on), don’t capitalize the name of the section.

What to capitalize:

Follow these rules when you use title-style capitalization.

Capitalize every word except:

Articles (a,an,the), unless an article is the first word or follows a colon

Coordinating conjunctions(and,but,or,nor,for,yet and so)

The word to in infinitives (HowtoInstallFlow)

The word as, regardless of the part of speech

Words that always begin with a lower case letter, such as iPad

Prepositions of four letters or fewer (at,by,for,from,in,into,of,off,on,onto,out,over,to,up and with), except when the word is part of a verb phrase
or is used as another part of speech (such as an adverb, adjective, noun, or verb):

Starting Up the Computer
Logging In to the Server
Getting Started with Your MacBook Pro

Use the em dash (—) to set off a word or phrase that interrupts or changes the direction
of a sentence or to set off a lengthy list that would otherwise make the syntax of a sentence
confusing. Don’t overuse em dashes. If the text being set off does not come at the end of the
sentence, use an em dash both before it and after it:

Setting just three edit points—the clip In point, the clip Out point, and the sequence In
point—gives you total control of the edit that’s performed.

To generate an em dash in a reStructured text, use ---.
Close up the em dash with the word before it and the word after it. Consult your department’s
guidelines for instructions on handling em dashes in HTML.